Bryce Harper pumps his fist as he trots home with the winning run as the Nationals pull off another miraculous triumph. (Jonathan Newton/The Washington Post)

What the Washington Nationals have done in the past nine days — nine straight wins, including four walk-offs — now borders on absurd. It has reached a point that Manager Matt Williams, who has spent a lifetime in baseball, can’t visibly share in his players’ excitement after the games because of the stress.

“It’s exciting for them,” the typically even-keeled Williams said. “It’s not a whole lot of fun in the dugout for the staff, but that’s okay.”

Wednesday’s 3-2 win over the Arizona Diamondbacks at Nationals Park brought the latest piece of walk-off drama. Anthony Rendon, initially given a night off by Williams after starting 62 straight games, was called upon to pinch-hit in the ninth with runners on the corners and one out.

Rendon rifled a shot down the third base line just beyond the reach of Arizona’s Cliff Pennington, scoring Bryce Harper with the winning run before Rendon was engulfed by jubilant teammates on the infield.

The win pushed the Nationals’ National League East lead over Atlanta to seven games. Afterward, Rendon expressed sympathy for his manager.

Tanner Roark allows just five hits and a lone walk in seven sterling innings Wednesday at Nats Park. (Jonathan Newton/The Washington Post)

“It’s a little stressful,” Rendon said. “Probably got some grays coming in now. But actually it’s good to be on the winning side of these walk-offs, for sure. As long as we get a ‘W,’ it’s a good time.”

Rendon’s heroics became necessary only after the usually reliable Tyler Clippard faltered.

Clippard took over for Tanner Roark (seven scoreless innings) and promptly walked leadoff hitter Jordan Pacheco to start the eighth. He then misplaced a fastball to left-handed batter Ender Inciarte, who smashed it into the home bullpen in right field to tie the game at 2.

Harper led off the ninth inning with a single up the middle. After Wilson Ramos struck out, Kevin Frandsen singled just beyond the reach of second baseman Aaron Hill. That set the stage for Rendon, who hammered the second pitch he saw from right-handed reliever Evan Marshall.

On the field, a now-common sight unfolded. Nationals players stormed out of the dugout and chased the hero. Head smacks, hugs, high-fives, jumping, cooler-dumping, messed-up hair and raucous cheering at Nationals Park.

“Just absolutely epic,” Harper said. “That’s the best word I can put on it. It’s been incredible. This team has a lot of fight. We’ve got a lot of heart, and we never die. We like to go out there and win ball games. Of course, it’s nice being in first place.”

Each of the four walk-offs have featured a different hero. Ramos delivered Saturday, Scott Hairston on Sunday and Adam LaRoche on Monday. Wednesday fell to Rendon, who sat on the bench for the previous eight innings.

Since the All-Star Break, Rafael Soriano has three blown saves and a 7.71 ERA in 11 appearances. The Post Sports Live crew debates whether the Nationals should be concerned by the closer's performances. (Post Sports Live/The Washington Post)

“A lot of guys around here will sing his praises all the time because he is so levelheaded,” Frandsen said. “For him to finally get a day off today, you’d never know, because he was out there doing everything. Coming off the bench, there’s one thing I think he was born to do, and it’s hit.”

The Nationals built a 2-0 lead when Ramos scored Ian Desmond with a groundball in the second (helped out by some aggressive base running from Harper to prevent an inning-ending double play) and back-to-back doubles from Asdrubal Cabrera and Jayson Werth in the sixth.

Roark worked out of a sixth-inning jam to keep the Diamondbacks at bay. He gave up a single to Pennington to start the frame and then an opposite field one-out single to Mark Trumbo, which allowed Pennington to take third. With the Nationals ahead by only one run, Roark needed outs.

He got Miguel Montero to mash a 1-0 sinker into the ground. The ball came back at Roark, who quickly darted to the side of the mound to field the ball and then spun to throw to second, where Desmond turned the inning-ending double play.

“He finds a way to make pitches when he needs to,” Williams said.

Clippard had gone more than four months between home runs allowed, from April 11 to Monday night. Now he has yielded home runs — and leads — in consecutive outings. What has led to the four walk-offs in five days has been mistakes by a previously steady bullpen: two blown saves by Clippard and one by Rafael Soriano.

Clippard gave up a single and got one more out in the eighth before Williams replaced him with Drew Storen. Despite giving up a stolen base and intentionally walking a batter, Storen escaped the jam, another scoreless outing in his stellar season. Soriano, after a recent rough patch and two days off, pitched a strong ninth inning, striking out one and hitting 93 mph with his fastball.

Then came the bottom of the ninth. Rendon knew he would bat with the pitcher’s spot coming up. Because he has little experience coming off the bench, he remembered the words of former Nationals teammate and pinch hitter Greg Dobbs: Treat it like your first at-bat of the game.

Rendon got a pitch he liked and smacked it down the third base line, and his teammates stormed the field.

“We’re a great team,” Harper said. “We know that coming into this clubhouse every single day. We come in here, ready to play, ready to win.”